Transmitter-mouthpiece.



0. F. PALK. TRANSMITTER MOUTHPI EGE. APPLICATION IIL'ED .TULY13,1909.

$967,747 Patented Aug. 16,1910.

(3 mm m/po-z UNITED STATES PATENT OFFICE.

OSCAR F. FALK, OF BELLEVILLE, NEW JERSEY, ASSIGNOR TO NA'IlIGNAL DIGTOGRAIPH COMPANY, A CORPORATION OF MAINE.

TRANSMITTER-MOU'IHPIEGE.

Specification of Letters Patent. Patented Aug, 16, 1910,

Application filed July 13, 1909. Serial No. 507,319.

To all whom it may concern:

Be it known that. I, OSCAR F. FALK, a

citizen of the United States, residing at Belleville, in the county of Essex and State piece for telephone transmitters, having a form of construction adapted to produce a purer and "louder transmission, or in other words, a more eflicient action of the sound delivered into N its receiving orifice than is obtained with the present simple conical or tapered passage.

Sound waves or vibrations travel in the manner of an enlarging sphere, and the zone or area of the spherical Wave which is projected against the orifice of any mouthpiece is partly concentrated by the use of the usual conical or' tapering construction thereof, in order to get an increased force against the diaphra Nevertheless this act-ion is not very e cient, the energy being reflected more outward than inward from the walls of the conical passage; moreover the energy .is reflected from the diaphragm itself without imparting any large percentage of force thereto.- If the waves reflected in thisway can be thrown back again in the direction of the diaphragm, a corresponding gain would evidently be secured. A still greater gain might be obtained from a third reflection, an

so on.

It is the purpose of my invention to accomplish this result and utilize practically all the energy of the sound wave which enters the telephone" transmitter mouthiece.

l/Vith this object in view'my invention consists in the features of construction and combination as hereinafter set forth and shown.

In the drawings: Figure l isa front elevation of a transmitter mouthpiece embodying the principles of my invention, and .Fig.

2 isa vertical sectional view of the same.

Referrin to the drawings in which like parts are esignated by the same reference sign, 1 designates a. conical or otherwise flaring or tapered passage, channel, tube or chamber, which communicates .at its small end with the sound inlet orifice of .a trans-' mitter casing 2.. i

. 3is a dis ed reflecting plate fixed. at the although it is evident that any skeleton mouth of the channel 1 with its convex side outward and ts concave side inward. This dished reflectlng plate is attached to the walls of the channel 1 in such a way as to provide an even or regular annular space 5 etwecn the two parts, through which sound from outside may enter. For this purpose I provide three connecting spokes or lugs at,

porting means desired may be used.

sound is guided to enter the annular opening by the adjacent inclined surface-sot the channel -1 and the dished reflecting plate 3. Within the transmitter mouthpiece the sound is in a sense trapped,and theoreticallyat least will'impart all its energy to the diaphragm. This is because any sound energy which is reflected in a backward directlon from the wall of the channel-1 or fromthe diaphragm itself, impinges immediately on the interior concave face of thedished re.

fleeting plate 3, and from this surface is again thrown back toward the diaphragm. This result is particularly eflicient as the dished reflecting plate resembles a para boloid in its general form, which as is well known, is most eflicient in reflecting sound along a given axis. This phenomenon must be distinguished from resonance in which. the sound waves act upon themselves to i11- crease the amplitude of vibration' As I understand the matter, the action is in the nature of giving the diaphragm repeated opportunitiesto subtract energy from every sound wave byrepeatedly causing suchl sound wave to be reflected back against the diaphragm surface. It is evident that'this action can take place equally well for sound 'Waves of all periodicity, so that there is no strong reinforcing. of certain notes as is the case with the phenomenon of'resonance.

The efiiciency of the apparatus depends largely on the fact that the tones of ordinary voice conversation are not very highly pitched so that the time interval betweeli succeeding waves is vastly greater than the successively reflected impulses of a single wave, whichmerge together in their effect on the diaphragm to produce a single in and out movement corresponding to the nature of the'particular wave received. In other words half a dozenor more reflections toeachv'vave may occur within the trans mitter mouthpiece and add theirefiect to produce a single movement of the dia": 

